Multi-ply fibrous sheet structure and its manufacture

ABSTRACT

In the manufacture of a multi-ply fibrous sheet structure, each of a pair of plies of fibrous web material is provided with a spot embossed first pattern defined by inwardly directed nested protuberances that are adhesively joined at distal surfaces thereof to confronting surfaces of the opposite ply, and the adhesively joined plies are provided with a spot embossed second pattern defined by registered, unidirectionally presented protuberances in each of the joined plies and fitted compactly one within the other.

This is a continuation of application Ser. No. 21,915, filed Mar. 19,1979 now abandoned.

BACKGROUND OF THE INVENTION

This invention relates to improvements in the manufacture of multi-plyfibrous sheet structures, particularly of the soft absorbent type suchas, for example, paper towels.

In the manufacture of paper towels, efforts have been directed toimproving important product qualities such as softness, waterabsorbency, and bulk. Softness, absorbency, and a degree of bulk havebeen imparted to multi-ply fibrous sheet structure by provision ofhighly repetitive patterns of relatively closely spaced emboss elementsin confronting plies. For aesthetics, a further desirable productquality, color patterns larger than the emboss elements have beenapplied. Softness, absorbency, bulk, and aesthetics have been enhancedby application of decorative, relatively widely spaced spot embosselements to confronting non-embossed creped plies, with or withoutapplication of color.

The following documents are representative of the prior art, and arebelieved material to the Examination of this application:

U.S. Pat. No. 2,834,809 discloses embossing rolls 22, 23 having meshedprotuberances 24 and depressions 25 for embossing a single ply of basestock 21 to form absorbent paper 20.

U.S. Pat. No. 3,556,907 discloses rolls 12, 13 for embossing separateplies 15 and 23 to form meshed embosses 17 and 25.

U.S. Pat. No. 3,673,060 discloses creped tissue webs joined by adhesivespots 34 upon passage between laminating rolls 28, 30. The joined websare embossed upon passage between embossing rolls 31, 32.

U.S. Pat. No. 3,775,231 discloses identical embossments A, B, and Cformed by passing a web 10 through three embossing stations defined byrubber rolls 13, 15, or 16 disposed about a single embossing roll 12.

Copending U.S. Patent application of the present inventor, Ser. No.116,230, filed Jan. 28, 1980, a continuation of abandoned applicationSer. No. 1,741, filed Jan. 8, 1979, now abandoned and assigned to theassignee of the present invention, discloses a spot emboss patternapplied to one side of a multi-ply fibrous sheet structure.

It is an objective of the present invention to provide a multi-plyfibrous sheet structure characterized by improved softness,absorptivity, bulk, and aesthetics through inclusion of a novelcombination of relatively small, closely spaced emboss elements withrelatively large, less closely spaced spot emboss elements.

It is a further objective of my invention to provide an improved methodand apparatus for forming multi-ply fibrous sheet structure of improvedabsorptivity, softness, bulk and aesthetics.

SUMMARY OF THE INVENTION

In achievement of the foregoing as well as other general objectives andadvantages, the invention contemplates fabrication of a multi-plyfibrous sheet structure comprising the provision, on each of a pair ofplies of fibrous web material, of an embossed first pattern defined byinwardly directed, nested protuberances at least some of which areadhesively joined at distal surfaces thereof to confronting surfaces ofthe opposite ply, and provision on the adhesively joined plies of asecond embossed pattern including protuberances registered,undirectionally, presented in each of the joined plies and fittedcompactly, one within the other.

The manner in which the objectives and advantages of the invention maybest be achieved will be more fully understood from a consideration ofthe following description, taken in light of the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a diagrammatic elevational view of apparatus contemplated bythe invention;

FIG. 2 is an enlarged fragmented sectional view of a portion of theapparatus and product taken in the plane of line 2--2 in FIG. 1, andlooking in the direction of arrows applied thereto;

FIG. 3 is a fragmented top plan view of the partially embossed fibroussheet structure, looking in the direction of arrows 3--3 in FIG. 1;

FIG. 4 is an enlarged fragmented sectional view taken in the plane ofline 4--4 in FIG. 3, looking in the direction of arrows applied thereto;

FIG. 5 is a fragmented top plan view of the fully embossed fibrous sheetstructure contemplated by the invention looking in the direction ofarrows 5--5 in FIG. 1; and

FIG. 6 is an enlarged fragmented sectional view of a portion of theproduct taken in the plane of line 6--6 in FIG. 5, looking in thedirection of arrows applied thereto.

DESCRIPTION OF THE PREFERRED EMBODIMENTS AND PRACTICE OF THE INVENTION

With more detailed reference to the drawing, and first to FIG. 1, anapparatus 10 includes a pair of embossing rolls 11 and 12 made ofsubstantially rigid material, such as steel, provided with meshing likepatterns to be described in detail in what follows. Rolls 11 and 12 areof like diameter, are mounted for rotation about parallel axes bysuitable drive means of known construction, and are so cooperablydisposed as to form a ply bonding nip.

A pair of embossing backup rolls 13 and 14 made of substantiallyflexible and resilient material, such as rubber, are mounted forrotation about parallel axes by known suitable drive means, and are socooperably disposed as respects steel rolls 11 and 12, respectively, toform embossing nips therewith.

A pair of webs 21 and 22 of paper, such as, for example, creped coarsefiber stock such as is used in paper toweling, are fed from suitablyarranged supply means (not shown) over rubber backup rolls 13 and 14,respectively. Web 21 is then fed between rolls 11 and 13 while web 22 isfed between rolls 12 and 14, and, as is seen from the showings of FIGS.2, 3 and 4, there is formed in each web the spot embossed patternsdefined by protuberances 11a and 12a on rolls 11 and 12.

Adhesive applicator means of conventional construction includes anapplicator roll 15 disposed for tangential engagement with web 21 onembossing roll 11. As web 21 is fed past applicator roll 15, adhesive isapplied to distal ends of emboss protuberances 21a. Continued rotationof the rolls drives webs 21 and 22 into the nip of rolls 11 and 12 fromwhich the webs exit as a partially completed multi-ply sheet structure23, each ply of which includes, as is seen to advantage in FIGS. 3 and4, a first spot embossed pattern defined by inwardly directed,relatively closely spaced nested protuberances 21a, 22a.

In special accordance with the invention, and with reference again toFIG. 1, a combined secondary embossing and laminating station 17 isprovided in apparatus 10 and comprises a flexible and resilientembossing backup roll 18 and a substantially rigid embossing roll 19,each mounted for rotation about an axis parallel to the other andforming a laminating nip through which sheet structure 23 passesadhesively to join distal ends of protuberance 21a to confrontingsurface of the opposite ply. As is seen to further advantage in FIGS. 5and 6, embossing and laminating roll 19 is provided with a pattern ofprotuberances 19a that imparts a larger, more widely spaced second, spotembossed pattern comprising protuberances 21b of greater extenttransversely of the sheet structure than the protuberances of rolls 11and 13. Sheet structure 23 is therefore transformed into an embossedsheet structure 23a of enhanced absorptivity, softness and bulk, whereinthe protuberances defining a first pattern are directed inwardly towardthe opposite ply and the protuberances defining a second pattern areregistered, are unidirectionally presented in each of the joined plies,and are fitted compactly one within the other throughout the extent ofeach said protuberance.

Considering the emboss patterns in more detail, and the improvedapparatus for achieving same, it is best seen in FIG. 2 that the meshedprotuberances 11a and 12a extend radially from steel rolls 11 and 12,respectively, to within a very short distance from the surface of theopposite roll. As is seen in FIG. 3, the protuberances 11a and 12adefine a closely spaced pattern featured by clusters of T-shapedelements which mesh with one another so that they produce a similarpattern of embossed protuberances 21a, 22a on each web 21 and 22, atleast some of which in the laminating nip are urged into engagement foradherence with intervening portions of an opposed web. The second, spotembossed pattern is featured by registered protuberances 21b compactlyfitted one within the other, arranged in a floral pattern for aestheticsand to impart additional bulk to the already embossed two-ply sheetstructure 23a.

In the embodiments thus far described, protuberances 11a and 12a havebeen illustrated as being in provision of nested web protuberances 21aand 21a. It will be understood, however, that they may be positioned toform point-to-point web protuberances. Protuberances 21a and 22a mayalso take shapes other than the linear configuration illustrated. Forexample, they may take the form of circular spots, or they may be formedas continuous line embossed elements. Also, the protuberances 21b maytake other shapes than the illustrated floral pattern, so long as theselected shape achieves the desired bulk and aesthetics. These and otherchanges are contemplated by the scope of the appended claims.

I claim:
 1. An absorbent fibrous sheet of papermaking fibers,comprising:two webs with inner surfaces facing each other, each webhaving a plurality of crests and depressions of a first pattern on itsinner surface; the crests on each web being positioned between thecrests on the other web and extending beyond the crests on the other webtoward the depressions on the other web; portions interconnecting crestsand depressions of one web being laterally spaced from portionsinterconnecting crests and depressions of the other web; meansconnecting at least some of the depressions of one web to the crests ofthe other web, whereby said webs are joined together to form said sheet;and said sheet being embossed as a unit to have formed therein aplurality of registered crests ad registered depressions of a secondpattern in each said web fitted compactly within one another throughoutthe extents of said crests and depressions, said crests of one of saidwebs extending beyond and spaced from the plane of the portion of saidone web having said first pattern of crests and depressions.
 2. Thesheet of claim 1, wherein the crests and depressions of said firstpattern in each said web are more closely laterally spaced from oneanother than are the crests and depressions of said second pattern insaid sheet.